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Dilated Cardiomyopathy

What is dilated cardiomyopathy?

Dilated cardiomyopathy (DCM) occurs when heart muscle cells are abnormal or damaged. Overall, it is quite rare in children. In many cases, DCM is genetic, that is, passed from parent to child through the chromosomes. Other less frequent causes include infection of the heart (such as viral myocarditis), endocrine (gland) problems, metabolic diseases, some chemotherapy drugs, and muscular dystrophy. In some children, the cause cannot be found.

The normal heart is a four-chamber pump whose beat is controlled by the heart’s electrical system. The heart walls are made of muscle cells that respond to the heart’s electrical impulse by briskly contracting (shortening). When the cells all contract together, the blood is pumped forward. In cardiomyopathy, the abnormal heart muscle cells prevent the heart from pumping with its normal vigor. The abnormal cells can also be a source of abnormal heart rhythms, called arrhythmias (see below).

How does this problem affect my child's health?

The health effects of DCM vary widely and depend on the degree of heart muscle damage. In mild cases, there may be no symptoms or only symptoms with exercise. In more severe cases, the heart is unable to pump enough blood to meet the body’s needs, causing symptoms of congestive heart failure. DCM can also be associated with abnormal heart rhythms including atrial flutter, atrial fibrillation, heart block, and ventricular tachycardia.

The course of the disease varies widely. If caused by myocarditis, the heart function improves (with medical treatment) in about one-third to one-half of patients. In others, the heart function can remain stable for long periods of time, but can worsen again many years later requiring more intensive medical treatment and, sometimes, even a heart transplant. In others, heart transplantation is needed right away.

How is this problem diagnosed?

Symptoms: Possible symptoms include palpitations (heart racing or "skipping" heart beats), low energy levels, and low exercise tolerance. Symptoms of congestive heart failure also include rapid breathing, clammy sweating, poor appetite, poor weight gain in young children, and swelling around the eyes, hand, and feet (more common in older children and young adults).

Physical findings: The exam depends on the degree of heart damage. If the damage is mild, the exam may be normal. If there is congestive heart failure, the heart rate and breathing rate are often fast. There may be a heart murmur (made by abnormal backward flow through the mitral valve) or other extra heart sounds and the liver is often enlarged.

Medical tests: An echocardiogram is the main test used to make the diagnosis and to measure the severity of the problem. Blood work is often done. Other heart tests include an electrocardiogram (ECG) and Holter monitor. On chest x-ray, the heart is usually enlarged. Sometimes a heart catheterization with a heart biopsy is done to confirm the diagnosis and help find the cause.

How is the problem treated?

In mild cases, treatment may not be needed. Heart medicines such as digoxin, lasix, and captopril or enalapril are used to control symptoms of congestive heart failure and to preserve or improve heart function. Blood thinners such as aspirin or warfarin (Coumadin) may be used to prevent clots from forming within the heart.

Rapid heart rhythms are treated by heart medicines and, if life-threatening, by an implanted cardioverter-defibrillator (ICD). For slow heart rhythms, a pacemaker may be needed.

A heart transplant may be needed if there are severe symptoms in spite of treatment with heart medicines.

What are the long-term health issues for my child?

The long-term health effects vary and depend on the degree of heart damage and the rate of disease progression. If the damage is caused by myocarditis, heart function can return to normal or near normal. In many children, DCM remains stable, given proper medical treatment, and health-related lifestyle changes are needed. In others, the problem can be very severe and if it does not respond to treatment, a heart transplant is needed.

SBE prophylaxis: Children with DCM are at increased risk for subacute bacterial endocarditis (SBE) if there is heart valve leakage. SBE is an infection of the heart caused by bacteria in the blood stream. Children with heart valve leakage heart are more prone to this problem because of the altered flow of blood through the heart. It can occur after dental work or medical procedures on the GI or respiratory tract because these procedures almost always result in some bacteria entering the blood. SBE can usually be prevented by taking an antibiotic prior to the procedure.

Exercise guidelines: An individual exercise program is best planned with the doctor so that all factors can be included. Children with DCM are often not allowed to play competitive sports. The children can usually participate in gym class but should be allowed to self-limit their level of exertion and they should not be graded (which could increase the pressure to exceed their natural limits).